Leadtime Leader Q&A: Mold Material Matters

MoldMaking Technology’s Leadtime Leader Award celebrates its 15th anniversary in 2018, so the magazine is asking past winners to share their perspective on a variety of industry issues, challenges and solutions. This month the magazine is examining mold material selection and innovation.

Understanding that mold material selection is application specific, what do you consider the most essential criteria? 

Rich Martin, business development manager, JMMS, Inc. (the 2011 honorable mention winner): The most essential is strength (or durability), based on warranty (or shot life) and customer specifications. 

Mike Zacharias, president, Extreme Tool and Engineering (the 2008 Small Shop Winner): When it comes to mold life, I consider machinability the lowest priority, which probably sounds odd from someone who builds molds. I look at thermal properties, durability and corrosion resistance first. 

Ryan Katen, general manager, Micro Mold (the 2013 honorable mention winner): Strength would be the most important in regard to wear resistance and longevity.

Ed Ergun, corporate sales manager, Concours Mold Inc. (the 2017 honorable mention winner): The most essential is thermal conductivity, as we use different material when we find areas that are hard to cool. 

Toby Bral, sales manager, MSI Mold Builders (the 2016 honorable mention winner): With strength as a given because the material must fit the application and annual volumes, machinability is the most important factor for most of the molds we build.  

What is the most important innovation in steels and alloys for moldmaking?

Martin: Advances in machine tools and cutter technologies for all mold materials are key innovations, as proficiency in machining and EDM processes across all tool steels is essential for every moldmaker.

Zacharias: I believe that the development of additive 
materials and performance alloys have been the biggest developments. The old standbys have been “tweaked” occasionally, but not much has occurred in the way of a significant development.

Katen: Improved properties through powder metallurgy technology is an important innovation.

Ergun: Steel manufacturers have done an excellent job of creating a library of steels for every application, which has enabled us always to find a way to make our molds work. 

Bral: Steel and aluminum grades that do not require stress relief have been the most important innovations. We make very large molds with blocks that require the removal of a lot of material, and we rarely stress-relieve the blocks. This helps us remain competitive from a lead-time perspective.  

Do you use copper mold alloys? Why or why not?

Martin: Yes, we use them for thermal conductivity. JMMS has been doing hybrid tooling for more than 15 years. 

Zacharias: Yes, we use them frequently and always for cycle-time benefit.

Katen: We use them infrequently, and only in selected applications for improved thermal conductivity.

Ergun: We do use copper for certain applications, but the applications are minimal for moldmaking.

Bral: We use copper mold alloys regularly when a customer agrees upfront, as they are considerably more expensive than other materials. They are very good at getting the heat out of an area and still stand up to more shots than aluminum. For the types of molds that we build, we restrict the use of copper mold alloys to areas of concern. We do not use copper mold alloys for very large areas or entire cavity or core halves, which is very cost prohibitive.  

Many engineered materials manufacturers are looking to develop mold materials based on the needs and wants that customers voice, so what would you like to see in a new mold material?

Martin: The silver bullet could be durability of H13 tool steel with the thermal conductivity of Moldmax.

Zacharias: Performance alloys (high thermal conductivity) with the strength and durability of steel and that are more easily machined like steel would be the next frontier in mold material development.

Katen: I would like to see improved hard-milling capabilities with tool steels in the 58–62 Rockwell hardness range.

Ergun: We love the benefits of one material but often cannot live with the negatives. For example, if we get thermal, we lose strength. If we get strength, we lose flexibility. If it is flexible, we lose surface finish, etc. So, a one-stop-shop mold material for all applications that machines at speed and is durable, thermal and cost-effective would be ideal. 

Bral: If you ask our customers, they would want something as strong as steel, as thermally conductive as aluminum but far less expensive than a copper alloy. That is probably not a reasonable expectation, so the decision will still come down to what meets the needs of the mold. Given materials that meet the performance requirement, we would want it to be very machinable, dimensionally stable and reasonably priced.